3458A reference boards on ebay
Most likely the boards are real, especially if the boards are from a seller in Colorado since that is where Keysight in the past manufactured and serviced all 3458A's. They still do all calibration in Loveland (I am not sure if Loveland is where service is done today) but this would mean the boards are pulls for either up grade to 002 or HFL boards or worse failed to meet spec. Further I would guess that working boards that meet spec would be retained for future replacements. That said the ones listed do appear genuine. If someone was thinking of duplicating the PCB I may be able to provide one to disassemble and repopulate afterwards. It would be interesting to have a few boards to experiment with.
Cheers;
Thomas Knox
Date: Fri, 30 Jan 2015 13:24:30 +0000
From: drkirkby@kirkbymicrowave.co.uk
To: volt-nuts@febo.com
Subject: Re: [volt-nuts] 3458A reference boards on ebay
On 30 January 2015 at 12:25, Will willvolts@gmail.com wrote:
The boards are factory rejects.
I doubt all boards on eBay are in this category. Some are probably
quite genuine, some may be rejects, and it would never surprise me if
some are counterfeit. The problem is, I have no idea what ones are
what.
I don't know what the problems sourcing the parts for making a
reference would be, but if a number of people wanted to make one from
parts, perhaps someone could produce a PCB and people contribute
towards the cost of it. Maybe leave people to get their own reference
chip, as there are different grades of that. But things like the
precision resistors may be easier to buy in a quantity of 10 rather
than 1.
I would certainly not mind buying one if a PCB was available. Even if
it works out costing a bit more than a 3458A reference from eBay, I'd
feel a bit happier.
Dave
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I'll be happy to design a PCB, and have bare PCB prototypes made.
Sourcing parts and purchasing them will be another, larger project!
Joel Setton
On 30/01/2015 14:24, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
On 30 January 2015 at 12:25, Will willvolts@gmail.com wrote:
The boards are factory rejects.
I doubt all boards on eBay are in this category. Some are probably
quite genuine, some may be rejects, and it would never surprise me if
some are counterfeit. The problem is, I have no idea what ones are
what.
I don't know what the problems sourcing the parts for making a
reference would be, but if a number of people wanted to make one from
parts, perhaps someone could produce a PCB and people contribute
towards the cost of it. Maybe leave people to get their own reference
chip, as there are different grades of that. But things like the
precision resistors may be easier to buy in a quantity of 10 rather
than 1.
I would certainly not mind buying one if a PCB was available. Even if
it works out costing a bit more than a 3458A reference from eBay, I'd
feel a bit happier.
Dave
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
Try this one... It has a 30 day return and you get a cal voltage with it.
On Fri, Jan 30, 2015 at 9:21 PM, Joel Setton setton@free.fr wrote:
I'll be happy to design a PCB, and have bare PCB prototypes made.
Sourcing parts and purchasing them will be another, larger project!
Joel Setton
On 30/01/2015 14:24, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
On 30 January 2015 at 12:25, Will willvolts@gmail.com wrote:
The boards are factory rejects.
I doubt all boards on eBay are in this category. Some are probably
quite genuine, some may be rejects, and it would never surprise me if
some are counterfeit. The problem is, I have no idea what ones are
what.
I don't know what the problems sourcing the parts for making a
reference would be, but if a number of people wanted to make one from
parts, perhaps someone could produce a PCB and people contribute
towards the cost of it. Maybe leave people to get their own reference
chip, as there are different grades of that. But things like the
precision resistors may be easier to buy in a quantity of 10 rather
than 1.
I would certainly not mind buying one if a PCB was available. Even if
it works out costing a bit more than a 3458A reference from eBay, I'd
feel a bit happier.
Dave
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/volt-nuts
and follow the instructions there.
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--
John Phillips
Am 31.01.2015 06:21, schrieb Joel Setton:
I'll be happy to design a PCB, and have bare PCB prototypes made.
Sourcing parts and purchasing them will be another, larger project!
Joel Setton
Here's my design in eagle, the prototype is working fine but there is
still room for improvement:
http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=rev0-econi.zip
Free for volt-nut useage, of course.
I tried to remove some voodoo that you will be told if using the
internet as source, but there are leftovers as I was afraid that they
could have something:
There are some extra cuts close to the connectors ("stress relief")
which are really unnecessary - after manufacture I became aware of a
experiment reported on EEVBlog that strong bending with a vise gave no
visible response of a LM399-based PCB on 6.5 digit DVMs.
A few drills around the LTZ itself which are cheaper to produce but
might or might not have some benefit - kovar lead and soldering joint
are thermally closer to the temperature controlled site, so less risk of
changing EMF voltages there.
The opamp at the output causes some tiny little degradation but gives a
lot of protection in case of accidents and abuse.
This core circuit can be pushed around to make it much more compact, if
somebody does it the regained space should be used to add some filtering
against EMI.
The resistors are not Vishay but Rhopoint Econistors. My LTZ1000A was
sourced from ebay, and no dud.
Hendrik
Hendrik,
Thanks for sharing your design. I have looked at the Rhopointasia.com
website and I noticed they had the squaristors. They appear to be of a
similar size to the Vishay metal foil resistors. It would appear you might
save some space on your design using radial packages. I have not seen these
mentioned by other users and I would be interested to see some real-world
data.
Todd
On Sat, Jan 31, 2015 at 2:59 AM, Hendrik Dietrich don_hendi@gmx.de wrote:
Am 31.01.2015 06:21, schrieb Joel Setton:
I'll be happy to design a PCB, and have bare PCB prototypes made.
Sourcing parts and purchasing them will be another, larger project!
Joel Setton
Here's my design in eagle, the prototype is working fine but there is
still room for improvement:
http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=rev0-econi.zip
Free for volt-nut useage, of course.
I tried to remove some voodoo that you will be told if using the internet
as source, but there are leftovers as I was afraid that they could have
something:
There are some extra cuts close to the connectors ("stress relief") which
are really unnecessary - after manufacture I became aware of a experiment
reported on EEVBlog that strong bending with a vise gave no visible
response of a LM399-based PCB on 6.5 digit DVMs.
A few drills around the LTZ itself which are cheaper to produce but might
or might not have some benefit - kovar lead and soldering joint are
thermally closer to the temperature controlled site, so less risk of
changing EMF voltages there.
The opamp at the output causes some tiny little degradation but gives a
lot of protection in case of accidents and abuse.
This core circuit can be pushed around to make it much more compact, if
somebody does it the regained space should be used to add some filtering
against EMI.
The resistors are not Vishay but Rhopoint Econistors. My LTZ1000A was
sourced from ebay, and no dud.
Hendrik
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